Device specific, carrier specific and software-load specific persistent data is typically written to non-volatile memory at the time the device is built in the factory. If any error is introduced at this build time, or if a carrier's requirements change after the build time, or if new features are introduced in subsequent software loads which require updated persistent data, no mechanism exists to update these previously-released devices except for recalling them to a service outlet for reconfiguration.
Further, even if a means for writing updated data to a wireless device existed, a potential problem is introduced for backward compatibility. A typical situation in which backward compatibility is required would be if the user has received a software update for their wireless device and then subsequently has downgraded their software load to the previous release. In this case, the new persistent data which is presented with the updated software load may not be supported by the previous software load, causing potential software errors on the wireless device.